/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.state;

import java.io.IOException;

/**
 * A storage location for one particular checkpoint, offering data persistent, metadata persistence,
 * and lifecycle/cleanup methods.
 *
 * <p>CheckpointStorageLocations are typically created and initialized via
 * {@link CheckpointStorage#initializeLocationForCheckpoint(long)} or
 * {@link CheckpointStorage#initializeLocationForSavepoint(long, String)}.
 */
public interface CheckpointStorageLocation extends CheckpointStreamFactory {

	/**
	 * Creates the output stream to persist the checkpoint metadata to.
	 *
	 * @return The output stream to persist the checkpoint metadata to.
	 * @throws IOException Thrown, if the stream cannot be opened due to an I/O error.
	 */
	CheckpointMetadataOutputStream createMetadataOutputStream() throws IOException;

	/**
	 * Disposes the checkpoint location in case the checkpoint has failed.
	 * This method disposes all the data at that location, not just the data written
	 * by the particular node or process that calls this method.
	 */
	void disposeOnFailure() throws IOException;

	/**
	 * Gets a reference to the storage location. This reference is sent to the
	 * target storage location via checkpoint RPC messages and checkpoint barriers,
	 * in a format avoiding backend-specific classes.
	 *
	 * <p>If there is no custom location information that needs to be communicated,
	 * this method can simply return {@link CheckpointStorageLocationReference#getDefault()}.
	 */
	CheckpointStorageLocationReference getLocationReference();
}
